᭜ EDITORIAL VIEWS Anesthesiology 2003; 98:1–2 © 2003 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Will Xenon Be a Stranger or a Friend? The Cost, Benefit, and Future of Xenon Anesthesia Xenon is both an old and a new anesthetic. Although its solubility. In our simulation, based on Japanese prices,18 anesthetic properties have been known for more than anesthetizing a 70-kg adult with 1 minimum alveolar 50 yr, it was largely forgotten until 1990,1 mainly because concentration of xenon (71%) for 240 min using a closed of its high cost. Aside from this problem, xenon possesses circuit requires approximately 16 l of xenon and costs US many of the characteristics of an ideal anesthetic. For ex- $167.00 (including the costs for oxygen, muscle relaxants, ample, its blood–gas partition coefficient is extremely small and the soda lime). This may actually be an underestimate, (0.115),2 yielding rapid emergence from anesthesia3 since the closed-circuit technique requires that the breath- regardless of the duration of anesthesia.4 It lacks teratoge- ing system occasionally be flushed and refilled to wash out nicity,5 and it produces analgesia,6 thereby suppressing nitrogen released from the patients’ body tissues. In con- Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/98/1/3/406339/7i0103000001.pdf by guest on 01 October 2021 hemodynamic and catecholamine responses to surgical trast, the costs of nitrous oxide and isoflurane are US stimulation.7,8 It is also a potent hypnotic.9,10 Unlike many $30.00 and $74.00, respectively, if a closed-circuit tech- conventional anesthetics, xenon does not produce hemo- nique or a total fresh gas flow rate of 3 l/min (i.e., nitrous dynamic depression in healthy humans11 and in dogs with oxide, 2 l/min, and oxygen, 1 l/min) are used. normal hearts and with cardiomyopathy,12 at least in part Obviously, this cost analysis depends on the price of because it has no actions on some important cardiac ion xenon, which has fluctuated a great deal over the last channels.13,14 The characteristics of xenon have been re- 20 yr due to the changing balance between supply and viewed more extensively elsewhere.15,16 demand within a dynamic market. The price was US Essentially all previous studies of xenon, even in humans, $4.00 in the late 1980s, increased to US $18.00 in 1998, have been relatively small. This issue of ANESTHESIOLOGY con- and then decreased to the current value of approxi- tains the first large-scale clinical evaluation of xenon anes- mately US $10.00. It is difficult to predict the future cost. thesia.17 The study, conducted by Roissant et al.,17 demon- However, even if the price of xenon is prohibitively high strates that xenon and nitrous oxide–isoflurane are at least at this time, technologic innovations in xenon produc- equivalent in efficacy and safety. This study is undoubtedly tion (and a growing market) may lead to lower costs. For a necessary step toward wide application of xenon. How- example, xenon does not have to be produced de novo ever, the real question is whether there is a true future for but can be retrieved from the waste anesthetic gas (i.e., xenon. In light of the work by Roissant et al.,17 it is reasonable recycling). Because the waste gas contains much higher to ask this question now. During the last decade, we have concentrations of xenon (e.g., 50 to approximately 60%) accumulated considerable knowledge about the actions of than does the air (0.087 ppm), its retrieval should be xenon. However, the answer to this question is not obvious. much less costly. The profit incentive may also promote international trade of xenon. Russia, for example, is a The Cost promising supplier, because the price of xenon is cur- rently US $5.00 or less in that country. Xenon currently costs approximately US $10.00 per liter. If one uses a closed breathing circuit, xenon anes- thesia is not as expensive as one might expect from the Can’t the Cost of Xenon Be Justified? price of the gas, because the amount of xenon absorbed Xenon enthusiasts argue that the gas has two advan- by the tissues is small as a result of its extremely low tages: environmental and medical. The environmental advantage is that xenon is not a greenhouse gas and, This Editorial View accompanies the following article: Rossaint hence, does not lead to global warming. It is also unre- ᭜ R, Reyle-Hahn M, Schulte am Esch J, Scholz J, Scherpereel P, active and, thus, should not affect the ozone layer, as do Vallet B, Giunta F, Del Turco M, Erdmann W, Tenbrinck R, nitrous oxide and volatile anesthetics. However, the is- Hammerle AF, Nagele P: A multicenter randomized comparison sue is not this simple. First, simply adopting a low-flow of the efficacy and safety of xenon and isoflurane in patients or closed-circuit technique can considerably reduce the undergoing elective surgery. ANESTHESIOLOGY 2003; 98:6–13. negative impacts of conventional anesthetics. Second, xenon is not perfectly environmentally friendly. Produc- Accepted for publication October 7, 2002. The authors are not supported by, ing1lofxenon gas requires 220 watt-hours of energy, a nor maintain any financial interest in, any commercial activity that may be million times more than that for nitrous oxide, because associated with the topic of this editorial. For research not related to this editorial, xenon has been provided to the authors by Koike Medical, Inc., Tokyo, xenon is purified by fractional distillation of the liquefied Japan, which may be viewed as a commercial competitor of Messer-Griesheim, air, which involves multiple heating, cooling, and pres- Krefeld, Germany. The authors view themselves as academic competitors of the 19 authors of the original article, simply because they are also working on clinical surization processes. This large energy consumption, xenon anesthesia. and the resultant emission of carbon dioxide, certainly Anesthesiology, V 98, No 1, Jan 2003 1 2 EDITORIAL VIEWS diminishes the environmental advantage of xenon. Even state by its lack of hemodynamic depression, leading to if xenon has measurable environmental advantages, it is better perfusion of vital organs? Does xenon improve very difficult to incorporate these in a cost-benefit anal- outcome in patients undergoing major surgery by pro- ysis because the value of the environment differs con- viding more optimal hemodynamics?§ Before answering siderably among different countries and societies. Fur- these questions, we cannot make a convincing conclu- thermore, environmental protection is considered a sion as to whether xenon is a stranger (after which the “public good” in an economic sense and, thus, cannot be gas is named) or a friend to anesthesiologists. 20 assigned to any individual economic entity. Takahisa Goto, M.D.,* Yoshinori Nakata, M.D., M.B.A.,† Shigeho Does xenon have medical advantages that justify the Morita, M.D.,‡ *Professor, ‡Professor and Chairman, Department of cost? The investigations over the past decade have revealed Anesthesia, Teikyo University School of Medicine, Tokyo, Japan. †Profes- sor, Department of Anesthesia, Teikyo University School of Medicine, many of its advantageous characteristics, but none of these Tokyo, and Teikyo University Ichihara Hospital, Ichihara-shi, Japan. appears sufficient to justify the cost by itself. Xenon pro- [email protected] vides faster emergence, but the difference is only a matter of minutes, and the time to ward readiness is not affected.17 References Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/98/1/3/406339/7i0103000001.pdf by guest on 01 October 2021 A lack of cardiac depression is certainly useful, but whether 1. Lachmann B, Armbruster S, Schairer W, Landstra M, Trouwborst A, Van Daal this represents a real clinical benefit is unclear, particularly GJ, Kusuma A, Erdmann W: Safety and efficacy of xenon in routine use as an since we are already doing a pretty good job anesthetizing inhalational anaesthetic. Lancet 1990; 335:1413–5 2. Goto T, Suwa K, Uezono S, Ichinose F, Uchiyama M, Morita S: The blood-gas millions of patients with fragile hearts. What we really need partition coefficient of xenon may be lower than generally accepted. Br J Anaesth is evidence that xenon improves outcome (i.e., results in 1998; 80:255–6 3. Goto T, Saito H, Shinkai M, Nakata Y, Ichinose F, Morita S: Xenon provides less morbidity and mortality). Such evidence is scarce, even faster emergence from anesthesia than does nitrous oxide-sevoflurane or nitrous for conventional anesthetics or anesthetic techniques, but oxide-isoflurane. ANESTHESIOLOGY 1997; 86:1273–8 4. Goto T, Saito H, Nakata Y, Uezono S, Ichinose F, Morita S: Emergence times xenon needs to be tested against this idealistic criterion from xenon anaesthesia are independent of the duration of anaesthesia. Br J because its cost is so high. Because the current anesthetics Anaesth 1997; 79:595–9 5. Lane GA, Nahrwold ML, Tait AR, Taylor-Busch M, Cohen PJ, Beaudoin AR: are so safe, it is unrealistic to expect that xenon will pro- Anesthetics as teratogens: Nitrous oxide is fetotoxic, xenon is not. Science 1980; duce measurable improvements in the outcomes of ordi- 210:899–901 6. Yagi M, Mashimo T, Kawaguchi T, Yoshiya I: Analgesic and hypnotic effects nary patients. Therefore, the target population will be high- of subanaesthetic concentrations of xenon in human volunteers: Comparison risk patients. In fact, the kinds of patients excluded from with nitrous oxide. Br J Anaesth 1995; 74:670–3 7. Nakata Y, Goto T, Morita S: Effects of xenon on hemodynamic responses to 17 the multicenter trial conducted by Rossaint et al.